Injection pump



Oct. 16, 1962 G. HFER ETAL INJECTION PUMP Filed Feb. 23, 1961 United States Patent Oiiiice 3,058,455 Patented Oct. 16, 19562 3,058,455 WJECTION PUMP Gerald Hfer and Franz Eheim, Stuttgart, Germany, 1assignors to Robert Bosch G.n1.b.H., Stuttgart, Germany Filed Feb. 23, 1961, Ser. No. 91,007 Claims priority, application Germany Feb. 24, 1960 14 Claims. (Cl. 12S-140) The present invention relates to fuel supply systems for internal combustion engines.

More particularly, the present invention relates to the injection pump type of fuel supply system for internal combustion engines.

With fuel supply systems of this type it is necessary, for efficient operation, to provide various controls. Thus, for starting purposes it is necessary that a relatively large amount of fuel be supplied by the injection pump to the engine while at idling speeds substantially less fuel is required to be delivered to the engine. Furthermore, controls are necessary to regulate the fuel output of the injection pump in the range from idling speed to maximum speed at full load, preferably in such a Way that fullsmoke-free combustion takes place. Finally, controls are necessary to limit the maximum engine speed in the event, for example, that there is a sudden decrease in the load.

At the present time the controls required for the above purposes are extremely complex -and require considerable skill on the part of the operator `as well as alertness.

One of the objects of the present invention is to provide a fuel supply system of the above type wherein all controls, except the contro-l which determines the idling speed of the engine, are fully automatic.

Another object of the present invention is to provide a fuel supply system of the above type wherein the only manually operable structure is `a throttle for the fuel supply, this throttle serving to determine the idling speed.

An additional object of the present invention is to provide ia fuel supply system of the above type with an automatic control structure, as referred to above, which is capable in a fully automatic manner of regulating the fuel output of the injection pump to -amounts which will provide total, smoke-free combustion `in the speed range from idling speed to maximum speed yat full load.

Still another object of the present invention is to provide a structure capable of accomplishing the above objects and at the same time being simple, rugged, compact and easily adjustable for providing optimum operation.

With the above objects in view, the present invention includes, in a fuel supply system for internal combustion engines, an injection pump having a cylinder means supported for axial movement and formed with a radial bore. An axially bored piston of the injection pump reciprocates in the cylinder means and has at all times a free end located therein, this piston being formed adjacent its free end with a radial bore passing from the interior to the exterior of the piston and communicating with the radial bore of the cylinder means during part of vthe stroke of the piston. A return-flow conduit means communicates with the radial bore of the cylinder means to return fuel therefrom back to `a fuel tank, and an enginedriven pump means communicates with the fuel tank and with "a supply conduit means for delivering fuel along the supply conduit means to the cylinder means at a pressure which increases and decreases with increases and decreases in the engine speed, respectively. A spring means cooperates with the cylinder means to maintain the latter at a rest position where .its radial bore is most distant from the radial bore of the piston when the latter is at the end of its suction stroke, and in this rest position of the cylinder means the injection pump will deliver the greatest amount of fuel to the engine. A pressureresponsive means communicates with the supply conduit means and lcooperates with the cylinder means to move the latter in opposition vto the spring means in a direction which locates the radial bore of the cylinder means vcloser to the radial bore of the piston, when the latter is at the end of its suction stroke, as the engine speed increases, so that the fuel output of the injection pump is automatically reduced as Vthe engine speed increases. ln addition, a manually operable throttle means is located in the supply conduit means to control the flow of fuel therethrough, and this manually operable throttle means is located downstream of the connection of the pressureresponsive means to the supply conduit means. This manually operable throttle `means forms the sole structure which determines the idling speed of the engine, Vwhile the axially movable cylinder means forms the sole structure .for determining .the maximum engine speed.

The novel features which -are considered as characteristic for the invention are ,set forth in particular in the appended claims. VThe invention itself, however, both as to its construction yand its method of operation, together with additional objects Iand yadvantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. l is a partly diagrammatic sectional elevation of one possible embodiment of a fuel supply system according to the present invention; and

FIG. 2 diagrammatlically illustrates the operation of the injection pump.

Referring now to FIG. l, there is shown therein van injection pump housing 1, 2 which includes the lower part 1 and the upper part Z fixed to the lower part 1. The drive shaft 3 of the injection pump is guided for rotation by the lower wall of the housing, and this shaft 3 is driven in a known way from the engine. Within the hollow space 51 of .the housing 1, ZIis located a cam disk 4 which is fixed rigidly to the shaft 3 for rotation therewith, as by being formed integrally therewith, for example. In the illustrated example the injection pump is designed to supply fuel to a four-cylinder engine, and therefore, the cam disk 4 is provided `with four camming portions 5 equidistantly distributed angularly labout the shaft 3.

The injection pump includes a piston 7 which is axially bored .throughout rits entire length, as shown in FIG. l, and it will be noted that the piston 7 is stepped so that the upper portion of the piston 7 is of smallest diameter, the intermediate portion is of intermediate diameter, and the lowermost portion, as viewed in FIG. l, is lof maximum diameter. This lowermost portion of the piston 7 forms the driven end thereof and takes the form of a flange S which for the greatest part of its thickness `is located within a recess formed in the upper end face of the cam disk 4. Of course, the piston 7 is coaxial with the shaft 3. A washer 9 engages the flange 3 and also engages the bottom end of a coil spring 11 which engages at its top end a thrust bearing 12 coaxial with rthe piston 7 and bearing lagainst the .housing part 2. Four rollers .6 lare supported .for rotation within the housing 1, as .indicated for two of the ro-llers in FIG. l, and these rollers are equidistantly distributed about the .shaft 3 and are engaged by the camming portions 5' of ythe disk 4. The spring 11 thus maintains the camming portions 5 at `all times in engagement with the rollers 6 whose axes of rotation, respectively, are stationary. A pin 13 is xedly carried by the cam disk t and extends into a cutout formed in the lflange 8` so that the piston 7 is constrained to rotate with the shaft 3 and disk 4. Of

' t course, the piston 7 will also be constrained to reciproc-ate axially with the shaft 3 and cam `disk 4.

The intermediate portion of the piston 7 is guided for axial movement by -a xylindrical guide 14 which is xed to the housing part 2 in the interior thereof as by having a press `lit therein. It will be noted that the piston v7 extends completely through the cylindrical guide 14 which remains stationary. The upper part of the piston 7, which is of smallest diameter, extends slidably into a cylinder means 15 to reciproca-te therein, and the free end of the `axially bored piston 7 is located at all times within the cylinder means 115. The housing part 2 forms a means which supports the cylinder means 15 for axial movement. A plug `16 closes the interior of the piston 7 at its end nearest the shaft 3, and this plug 16 is pressed against by one end of a spring 17 whose other end presses .the nonreturn valve 18 upwardly, as viewed in FIG. l, against Ia valve seat formed by a frustoconical shoulder in the interior of the piston 7. Thus, the spring 17 urges the valve '18 to its closed position engaging this valve seat. In its illustrated closed position, the valve 18 separates the working or pumping chamber 19 of the injection pump from the pressure chamber 2t? within the piston 7. -The valve `18 is xed at its end which is directed toward the chamber 119 to a guide which is freely slidable within the piston 7 land which is formed with axial grooves providing free communication between the chambers 19 and 20 whenever the valve 18 is displaced from its seat. The piston 7 is formed with -a radial bore 21 communicating with the pressure chamber 20, and the guide cylinder 14 is formed with four radial bores 22 with which the bore 21 successively communicates. Only one of the bores 22 is shown in the drawing for the sake of clarity. The housing part 2 is formed with a discharge passage 23 communicating with each bore 22 and terminating in an outlet opening 24. A tube 25 is uidtightly connected with each outlet 24 and communicates with an injection nozzle 26. These nozzles are located in a conventional manner in the engine communicating with the cylinders thereof to deliver fuel thereto.

The piston 7 .is also formed with four radial bores 27 whose axes are located in a common plane normal to the axis of the piston 7, and these four radial bores 27 are uniformly distributed about the axis of the piston. These bores 27 communicate successively with a supply conduit means formed in part by the radial bore 28 of the guide cylinder 14. Thus, the bores 27 successively communicate with the bore 23 of the supply conduit means which includes in addition to the bore 28, the bore 29 formed in the housing part` 2 and forming an extension of the bore 2S and the tube 6G which is uidtightly connected with the bore 29. A manually operable throttle means 30 is located in the supply conduit means to control the flow of fuel therefrom to the charnber 19 which is located in part Within the cylinder means 15, `and this manually operable throttle means 30 is in the form of a rotary valve member passing transversely across the bore 29 and formed with a bore which may be positioned coaxially with the bore 29 in the angular position of the valve 30 shown in solid lines in FIG. l. Any suitable mechanical transmission is accessible to the operator and connected to the valve 39 to enable the operator to position the valve 3) at a selected angular position.

A spring means 31 is provided to oppose axial movement of the cylinder means 1'5 in a downward direction, as viewed in .iF-IG. l, and this spring means 31 takes the form of a coil spring which bears at its bottom end `against Vthe stationary guide cylinder 14. At its top end the spring 3'1 bears against a snap ring 32 located in a groove formed in the exterior of the cylinder means 15. The spring 31 yieldably maintains the cylinder means 15 in its rest position illustrated in FIG. l where a `hollow cap member 33 threadedly connected to the cylinder 15 bears against a plug 34 threaded into the top end of the housing part 2. This plug 34 closes a chamber 35 which surrounds the cylinder means 15 and which is formed within the upper portion of the housing part 2. An adjusting screw 36 is threadedly carried by the plug 34, and a lock nut 37 is threadedly carried by the screw 36 for iixing the axial position thereof. An elongated pin 38 is pro- .vided at its bottom end with an enlarged head 39 which is cylindrical and which has a duid-tight slidable fit within the cylinder means 15. This head 39 of the pin 3S has a tit in the cylinder 15 which is as tight as possible while enabling the cylinder 15 to slide axially with respect -to the head 39. This head 39 of the pin 38 provides the upper boundary of the pump chamber 19. At its end distant from its head 39 the pin 38 iixedly carries .a collar 41 which is located within a cutout formed in the screw 36. For example, the screw 36 may be formed at its Ibottom end with a T-slot which receives the collar 41 in the manner illustrated in FIG. l, so that in this way the screw 36 may be turned for adjusting the axial position of the head 39. The cap 33 which is xed to the cylinder 15 for movement therewith has at its top end, yas viewed in FIG. l, an annular wall engaged by the top end of a spring 42 which forms, as will be apparent from the description below, an additional spring means for opposing axial movement of the cylinder means 15. The spring 42 presses at its bottom end, as viewed .in FIG. l, against a washer 43 located against the upper end, as viewed in FIG. l, of the cylinder means 15. The cylinder means 15 is formed with an inner shoulder 44, directed toward the washer 43 and engaged by a washer 45, and between the washers 43 and 45 is located an annular dished spring 46 which forms still another spring means opposing axial movement of the cylinder means d5, as will be apparent from the description which follows.

The cap 33 forms together with the upper end of the cylinder -15 a pressure-responsive means which cooperates with the cylinder means 15 for moving the latter automatically in response .to pressure changes in the fuel within the supply conduit means 60, 29, 28, and for this purpose the housing part 2 is formed with a bore 47 providing communication between the chamber 35 and the supply conduit means at a part thereof located upstream of the throttle means 30. The cap 33 is provided with Ian opening 48 which provides communication between the interior 33' of the cap 313 and the chamber 35.

The cylinder means 15 separates the chamber 35 from a chamber 49 in the housing part 2 which receives the Spring means 31. This chamber 49 forms part of a return-flow conduit means which serves to return fuel lfrom a radial bore 52 formed in the cylinder means 15 to a fuel tank 56 shown digrammatically at the bottom of FIG. 1. This return-flow conduit means includes, in Aaddition to the chamber 49, a bore 50 formed in the housing part 2 and the chamber 51 formed by thehousing part 1. In addition, the return-flow conduit means includes the tube 62 leading lfrom the chamber 51 to the tank 56, and this tube 62 carries la non-return valve 63. The non-return valve 63 automatically opens in response to a relatively small increase in pressure and serves to prevent emptying of the chambers 49 and 51.

The piston 7 is formed adjacent its upper free end, which is located at all times within the cylinder means 15, with at least one radial bore 54 communicating with an annular groove 53 formed in the exterior of the piston 7, and in this way the pump chamber 19 which extends between the head 39 of the pin 38 and the valve 18 communicates at all times with the groove 53. During a part of the stroke of the piston 7 the groove S3 overlaps the bore 52 so that during a part of the stroke of the piston 7 the radial bores 52 and 54 will communicate with each other, and of course at this time fuel will flow from the chamber 19 through the bores 54 and 52 back through the return-dow conduit means 49, 5t), 51, 62 to tank 56.

An engine-driven pump 57 communicates with the tank 56 and through a lter 59 with the tube 60, so that in this way fuel is pumped from the tank 56 to the supply conduit means 60, 29, 2S, and the engine-driven pump 57 forms a means which supplies fuel along the supply conduit means at pressures which increase and decrease as the engine speed increases and decreases, respectively. A non-return valve 61 communicates through a suitable conduit with the discharge side of the pump 57 and with the conduit 62, and this valve 61 will open when a predetermined pressure is reached in the supply con duit means for directing the overow fuel back to the -tank 56. Upstream of the non-return overflow valve 61 is located a throttle 61' which contributes to the maintenance in the supply conduit means 60, 29, 2S of a fuel pressure which is dependent upon the speed of operation of the pump 57 and thus upon the speed of the engine which drives the pump 57.

The above-described structure operates as follows:

The piston 7 is shown in FIG. l at the end of its suction stroke. During further turning of the cam disk 4 a pressure stroke of the piston 7 commences, vand during the initial part of the pressure stroke the bore 2'7 which communicates with the bore 28 turns away from the latter so that the piston now closes the bore 2S and thus the supply conduit means no longer communicates with the pump chamber 19. The instant that the bore 2S is closed, the effective pressure stroke starts and continues until the bores 54 communicate through the groove 53 with the bore 52. The fuel in the chamber 19 acts, during the effective pressure stroke of the piston to open the valve 18 in opposition to the spring 2G so that the fuel ows at this time into the pressure chamber 20 and from there through the bore 21 into one of the bores 22 and then on through the passage 23 which communicase therewith and the conduit 25 to the injection nozzle 26 of the particular cylinder.

Of course, during the subsequent suction stroke of the piston 7 the next bore 27 will come into communication with the bore 28 so that the fuel will again have iilled the chamber 19 by the time the piston 7 reaches the end of its suction stroke.

During the portion of the pressure stroke of the ,piston 7 subsequent to the instant when the bores 54 and 52 communicate with each other, the valve 18 closes and the fuel ows from the chamber 19 through the bores 54 and 52 and the return-flow conduit means 49, Si), .51, 62 back to the tank 56, the pressure of the fuel upstream of the valve 63 being suflicient to automatically open this valve at this time. In the rest position of the cylinder means 15 shown in FIG. l and in the solidline position of the throttle means 311 the fuel output of the injection pump of the invention is at a maximum. This maximum fuel output is necsary for starting the internal combustion engine. In the diagram of FIG. 2, the ordinate indicates the quantity of fuel delivered by the injection pump, and the total of the amounts indicated at a, b and c is the amount of fuel delivered by the pump when the engine is started.

Once the engine has started the pressure of the fuel delivered by the pump 57 increases and thus the pressure of the fuel within the chambers 35 and 33 increases, and the result is that the pressure-responsive means formed by the cap 33 and the top end of the cylinder 15 acts in response to this increase in pressure to move the cylinder means 15 in opposition to the spring means 31 downwardly, as viewed in FIG. 1. This movement takes place at this time only in opposition to the spring means 31 through the increment of movement a whichl is the axial distance between the top face of the head 39 and the washer 45. When the cylinder means 15 has moved through the increment a', the washer 45 will engage the top face of the head 39 of the pin 38. As a result the fuel output of the injunction pump will be diminished by the amount a shown in FIG. 2. This decrease in fuel output is brought about by the fact that the radial bore 52 of the cylinder means 15 becomes located closer to the radial bores 54, so that the latter communicate with the bore 52 at an earlier part of the pressure stroke of the piston 7 than when the cylinder means 15 is in its rest position shown in FIG. l, and thus less fuel is delivered from the chamber Ztl to the engine cylinders.

If it is desired to operate the engine at idling speed, ythe operator turns the throttle valve 36 so that its passage -has approximately the 4inclined position shown in dotted lines in FIG. l, and in this way the cross section of the -bo-re 29 through which the fuel can flow is greatly reduced. The fuel output at this time is shown by the dot-dash line at the lower left portion of FIG. 2, and the idling speed is indicated -at n along the abscissa of :the diagram of FIG. 2. The throttle means 36 forms the only `structure for determining the idling speed nl, and in fact the throttle means 30 is the only part of the structure of the invention which is operated manually.

In order to increase the engine speed the throttle means y30 is again returned to the solid line position shown in FIG. l. Insofar as the load on the engine permits, the engine speed will increase to the highest engine speed at full load indicated at n2 in FiG. 2. Inasmuch as the pressure in the chambers 3'5 and 33 increases vduring the increase in the engine speed from n1 t-o n2, the pressure-responsive means acts to displace the cylinder means 15 further in a `downward direction, las viewed in FIG. l, and during this time the cylinder means 15 will be displaced through a second increment b. During this second increment `of movement b the spring means 46 as Well as the spring means 31 opposes the movement of the cylinder means 15. rfhus, the shoulder 4,4 moves away from the washer 45 which remains in engagement with the head 39 and at the end of the increment b the spring 46 will ybe lat and will have its opposed faces parallel to and engaging the washers 45 `and 43. Thus, the bore 52 will become located closer to the bores 54 when the piston 7 is at the end of its suction stroke, `and the fuel output will therefore be further reduced. This reduction will be by the lamount indicated at b in PIG. 2. This reduction b serves to adapt the fuel supply to the engine cylinders to the largest amount of fuel which will provide full, smoke-free combustion in the engine cylinders.

In the event that the load decreases so that the engine speed increases beyond the speed n2, there will be a further increase in the pressure within the chambers 35 and 33', and now there will be a further action of the pressure-responsive means to displace the cylinder means 1'5 beyond the increments a and b in a downward direction, as viewed in PIG. l, and the spring means 42 :acts only beyond the increment b to oppose the movement of the cylinder means 15. Thus, at this time the top end of the cylinder 15 will move downwardly away from the washer 43 while the washer i5 remains in en- `gagement with the head 39. Thus, the bore 52 will approach even closer to the bores 542 when the piston 7 is at the end of its suction stroke, and therefore the fuel output will be further reduced along the range c indicated in FIG. 2. At complete unloading of the engine, the engine can only reach the maximum engine speed n3 indicated in FIG. 2. Thus, this limitation on the maximum engine speed is 'brought about .'by the movement of the cylinder means 15 in response to the increase in the pressure of the fuel delivered `by the pump 57.

It will be noted that with the above structure the spring means 31 acts -duringthe entire movement of the cylinder means 15 to oppose movement thereof downwardly from its rest position shown in FIG. Yl, and this spring means 31 is the yonly spring means which acts during the iirst increment of movement a. The spring means 46 acts only during -t-he second increment of movement, and

the spring means 42 acts only when the cylinder means I moves beyond the second increment of movement.

Inasmuch as the forces lwith which the springs 31, 46 and 42 urge the cylinder 15 back toward its rest position depends upon the pressure of the fuel delivered by the pump 57 `and thus changes in vaccordance with changes in the engine speed, and inasmuch as the fuel output of the injection pump depends upon the effective pressure stroke of the piston '7, which is to say upon the axial position lof the cylinder means 15, the coordinates of FIG. 2 may indicate the values shown in parentheses in FIG. 2. lThus, the abscissa may indicate the spr-ing forces urging the cylinder means l5 back to its rest position shown by p, lwhile the ordinate may indicate the extent of movement of the cylinder means shown by the value s. In this event the graduations of the ordinate s increase in a downward direction and have a zer-o value at the maximum fuel output.

It will thus be seen that the axially movable cylinder means of the invention performs the following functions:

(a) In the range of speeds from the starting speed to idling speed `of the engine, it `decreases the fuel output of the injection pump -by the amount required for starting the engine;

(b) In the range from idling speed to the highest engine speed `at full load, it adapts with the fuel output to the engine cylinders to the largest amount which will provide full, smoke-free combustion; and

(c) In the range of speeds higher than the highest speed at full load, it limits the maximum engine speed.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of fuel supply systems differing from the types described above.

While the invention has een illustrated and described as embodied in injection pump type of fuel supply systems, it is not intended to lbe limited to the details shown, since various modications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can :by applying current knowledge readily adapt it for various Iapplications with-out omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended Within the meaning and range of equivalence of the following claims.

What is claimed `as new `and desired to 'be secured by Letters Patent is:

l. In a fuel supply system for internal combustion engines, in combination, an injection pump having an axially bored piston and a cylinder means in which said piston reciprocates, said cylinder means land piston defining a pumping chamber from which fuel is pumped to the engine and said piston having a free end located at all times in said cylinder and being formed adjacent said free end with at least one radial bore passing from the interior of said piston to the exterior surface thereof, said cylinder means being formed also with at least one radial bore with which said radial bore of said piston communicates during part of the stroke of said piston; means communieating with said radial bore of said cylinder means for directing fuel therefrom back to a fuel tank; and means cooperating with said cylinder means for automatically regulating the axial position thereof only in accordance with the speed of the engine which is supplied with fuel by said injection pump so that the moment of communication between said radial bores will vary only with variations in engine speed, the axial positioning of said cylinder means being the sole control for the maximum speed of the engine.

2. In a fuel supply system for internal combustion engines, in combination, an injection pump having an axially bored piston and an axially movable cylinder means in which said piston reciprocates, said piston having a free end located at all times in said cylinder means and formed adjacent said free end with a radial bore passing from the interior of said piston to the exterior surface thereof and said cylinder means being formed also with a radial bore passing therethrough and communicating with said radial bore of said piston during a part of the stroke thereof; supply conduit means communicating with said injection pump for supplying fuel thereto from a fuel tank; return flow conduit means communicating with said radial Ibore of said cylinder means for directing fuel therefrom back to said tank; manually operable throttle means cooperating with said supply conduit means for regulating the ow of fuel to said injection pump, said throttle means forming the sole structure for determining the idling speed of the engine; spring means urging said cylinder means in one direction; and automatic pressure-responsive means cooperating with said cylinder means and responding only to the pressure of fuel in said supply conduit means for automatically determining the axial position of said cylinder means in opposition to said spring means in accordance with the pressure of the fuel in said supply conduit means so as to control the moment when said radial bores communicate with each other, said automatic means being the sole structure for determining the maximum speed of the engine.

3. In a fuel supply system for internal combustion engines, in combination, an injection pump having an axially bored piston and an axially movable cylinder means in which said piston reciprocates, said piston having a free end located at all times in said cylinder means and formed adjacent said free end with a radial bore passing from the interior of said piston to the exterior surface thereof and said cylinder means being formed also with a radial bore passing therethrough and communicating with said radial bore of said piston during a part of the stroke thereof; supply conduit means communicating with said injection pump for supplying fuel thereto from a fuel tank; means cooperating with said supply conduit means for maintaining fuel therein at a pressure which varies directly with variations in engine speed; return flow conduit means communicatin g with said radial bore of said cylinder means for directing fuel therefrom back to said tank; manually operable throttle means cooperating with said supply conduit means for regulating the flow of fuel to said injection pump, said throttle means forming the sole structure for determining the idling speed of the engine; spring means urging said cylinder means in one direction; and automatic pressure-responsive means cooperating with said cylinder means for automatically determining the axial position thereof in opposition to said spring Ameans in accordance with the fuel pressure in said supply conduit means and therefore the speed of the engine so as to control the moment when said radial bores communicate with each other, said automatic means being the sole structure for determining the maximum speed of the engine, said automatic means performing the following functions:

(a) In the speed range from starting speed to idling speed, reducing the amount of fuel delivered to the engine to the extent necessary for starting the engine;

(b) In the speed range from idling speed to the highest speed at full load, regulating the amount of fuel delivered to the engine to the maximum amount which will burn with smoke-free full combustion; and

(c) In the speed range higher than the maximum full load speed, limiting the maximum permissible engine speed.

4. In a fuel supply system for internal combustion engines, in combination, an injection pump including an axially bored piston and means for reciprocating the same from one dead-center position at the end of its suction stroke axially along a pressure stroke to an opposed deadcenter position and then back to said one dead-center position, said injection pump including an axially movable cylinder means in which said piston reciprocates, said piston having a free end located at all times in said lcylinder means and being formed adjacent said free end With at least one radial bore, and said cylinder means also being formed with a radial bore which communicates with said radial bore of said piston during a part of the stroke thereof; a fuel tank; retum-iiow conduit means communicating with said radial bore of said cylinder means and said tank for returning fuel from said radial bore of said cylinder means to said tank; supply conduit means communicating with the interior of said cylinder means for supplying fuel thereto; engine-driven pump means communicating with said tank and said supply conduit means for supplying fuel at pressures which'vary proportionateiy With the engine speed along said supply conduit means to said cylinder means; spring means operatively connected to said cylinder means for urging the same to a rest position where said radial bore thereof is at its greatest distance from said radial bore of said piston when the latter is at the end of its suction stroke so that fuel will not be returned to said tank until said radial bores communicate with each other, thus providing the largest supply of fuel to the engine when said cylinder means is in said rest position thereof; and pressure-responsive means cooperating with said supply conduit means for urging said cylinder means from said rest position to positions Where said radial bore of said cylinder means is located closer to said radial bore of said piston, when the latter is at the end of its suction stroke, as the engine speeds increase, so that With increasing engine speed the radial bore of said piston will communicate with the radial bore `of said cylinder means at earlier moments during the pressure strokes of said piston to reduce automatically the fuel supply to the engine as the engine speed increases.

5. In a fuel supply system for internal combustion engines, in combination, an injection pump including an axially bored piston and means for reciprocating the same from one dead-center position at the end of its suction stroke axially along a pressure stroke to an opposed dead-center position and then back to said one deadcenter position, said injection pump including an axially movable cylinder means in which said piston reciprocates, said piston having a free end located at all times lin said cylinder means and being formed adjacent said free end with at least one radial bore, and said cylinder means also being formed with a radial bore which communicates with said radial bore of said piston during a part of the stroke thereof; a fuel tank; return-now conduit means communicating with said radial bore of said cylinder means and said tank for returning fuel from said radial bore of said cylinder means -to said tank; supply conduit means communicating with -the interior of said cylinder means for supplying fuel thereto; engine-driven pump means communicating with said tank and said supply conduit means for supplying fuel at pressures which vary proportionately with the engine speed along said supply conduit means to said cylinder means; spring means operatively connected to said cylinder means for urging the same to a rest position where said radial bore thereof is at its greatest distance from said radialbore of said piston when the latter is at the end of its suction stroke so that fuel will not vbe returned to said tank until said radial bores communicate with each other, thus providing the largest supply of fuel to the engine when said cylinder means is in said rest position thereof; pressure-responsive means cooperating with said supply conduit means for urging said cylinder `means from said rest position to positions where said radial bore of said cylinder means is located closer to said radial bore of said piston, when the latter is at the end of its suction stroke, as the engine speeds increase, so that with increasing engine speed the radial bore of said piston will communicate with the radial bore of said cylinder means at earlier moments during iii the pressure strokes of said piston to reduce automatically the fuel supply to the engine as the engine speed increases; and manually operable throttle means located in said supply conduit means downstream of the place where sai pressure-responsive means communicates With said supply conduit means, said throttle means regulating the oW of fuel to said cylinder means of said injection pump and said throttle means being the only manually operable structure of the entire fuel supply system.

6. in an injection pump, in combination, cylinder means having a Wall portion formed with a radial bore; support means supporting said cylinder means `for axial movement; an axially bored piston coaxial With and slidable Within said cylinder means; means for reciprocating said piston along pressure and suction strokes, said piston having a free end located at all times in said cylinder means and said axial bore of said piston communicating at all times with the interior of said cylinder means, said piston being formed adjacent said free end thereof With a radial bore which communicates with said radial bore of said cylinder means during part of the stroke o f said piston; a fuel tank; return-now conduit means communicating with said radial bore of said cylinder means and said tank for conveying f-uel from said radial bore of said cylinder means back lto said tank; first spring Vmeans c ooperating W-ith said cylinder means for yieldably maintaining the latter in a rest position Where said radial bore thereof is at its maximum distance from said radial Lbore of said piston When the latter is at the end `of its ysuction stroke; supply conduit means communicating with ythe interior of sai-d cylinder means for supplying fuel thereto; engine-driven pump means communicating With said tank and supply conduit means for pumping fuel along said supply conduit means to said cylinder means at pressures which increase and decrease with an increase and a decrease in the yengine speed, respectively; pressure-responsive means communicating With said supply conduit means and cooperating with said cylinder -means for urging the latter in yopposition -to said first spring mean-s in a direction 'locating said radial bore of said cylinder means closer to said radial bore of said piston when the latter is at the ,end of its suction stroke, said rst spring means forming the only means opposing movement of said cylinder means in said direction from said rest Aposition thereof during a first increment of movement of said cylinder means; and second spring means cooperating with said cylinder means yfor opposing movement thereof in said direction only during a second incrementof lmovement of said cylinder means subsequent to said irst iucrement.

7. In an injection pump, in combination, cylinder means having a Wall portion formed with a radial bore; support means supporting said cylinder means for axial movement; an axially `bored piston coaxial with and slidable within said cylinder means; means for reciprocating said piston along pressure and suction strokes, said piston having a free end located at -all times in said cylinder means and said axial 'bore of said piston communicating at all times with the interior of said cylinder means, said piston being formed adjacent said free end thereof -vvith a radial bore which communicates with said radial bore of said cylinder means duringpart of the stroke of said piston; a fuel tank; return-ilow conduit means communieating With said radial bore of said cylinder means and said tank for conveying fuel `from said radial bore of said cylinder means back to said tank; first spring means cooperating With said cylinder means for yieldably `maintaining the latter in a rest position Where said radial bore thereof is at its maximum distance from `said radial bore of said piston When the latter is at the end of fits suction stroke; supply conduit means communicating with the interior of said cylinder means for supplying fuel thereto; engine-driven ypump means communicating with said tank and supply conduit means for pumping fuel along said supply conduit means to said cylinder means at pressures which increase and decrease with an increase and a decrease in the engine speed, respectively; pressure-responsive means communicating with said supply conduit means and cooperating With said cylinder means for urging the latter in opposition to said first spring means in a direction locating said radial bore of said cylinder means closer to said radial bore of said piston when the latter is at the end of its lsuction stroke, said rst spring means forming the only means opposing movement of said cylinder means in said direction from said rest position thereof during a first increment of movement of said cylinder means; second spring means cooperating with said cylinder means for opposing movement thereof in said direction only during a second increment of movement of said cylinder means subsequent to said first increment; and third spring means cooperating with said cyiinder means for opposing movement thereof in said direction only subsequent to said second increment of movement of said cylinder means.

8. In an injection pump, in combination, cylinder means having a wall portion formed with a radial bore; support means supporting said cylinder means for axial movement; an axially bored piston coaxial with and slidable within said cylinder means; means for reciprocating said piston along pressure and suction strokes, said piston having a free end located at all times in said cylinder means and said axial bore of said piston communicating at all times with the interior of said cylinder means, said piston being formed adjacent said free end thereof with a radial bore which communicates With said radial bore of said cylinder means during part of the stroke of said piston; a fuel tank; return-How conduit means communicating with said radial bore of said cylinder means and said tank for conveying fuel from said radial bore of said cylinder means back to said tank; first spring means cooperating with said cylinder means for yieldably maintaining the latter in a rest position where said radial bore thereof is at its maximum distance from said radial bore of said piston when the latter is at the end of its suction stroke; supply conduit means communicating with the interior of said cylinder means for supplying fuel thereto; engine-driven pump means communicating with said tank and supply conduit means for pumping fuel along said supply conduit means to said cylinder means at pressures which increase and decrease with an increase and a decrease in the engine speed, respectively; pressure-responsive means communicating With said supply conduit means and cooperating with said cylinder means for urging the latter in opposition to said first spring means in a direction locating said radial bore of said cylinder means closer to said radial bore of said piston when the latter is at the end of its suction stroke, said `first spring means forming the only means opposing movement of said cylinder means in said direction from said rest position thereof during a first increment of movement of said cylinder means; and second spring means cooperating with said cylinder means for opposing movement thereof in said direction only during a second increment of movement of said cylinder means subsequent to said first increment, said first increment of movement of said cylinder means providing a reduction in the amount of fuel delivered by said injection pump to the engine in the speed range from starting to idling speed.

9. In an injection pump, in combination, cylinder means having a wall portion formed with a radial bore; support means supporting said cylinder means for axial movement; an axially bored piston coaxial with and slidable within said cylinder means; means for reciprocating said piston along pressure and suction strokes, said piston having a free end located at all times in said cylinder means and said laxial bore of said piston communicating at all times With the interior of said cylinder means, said piston being formed adjacent said free end thereof with a radial bore which communicates with said radial bore of said cylinder means during part of the stroke of said piS- ton; a fuel tank; return-flow conduit means communicating with said radial bore of said cylinder means and said tank for conveying fuel from said radial bore of said cylinder means back to said tank; first spring means cooperating With said cylinder means for yieldably maintaining the latter in a rest position Where said radial bore thereof is at its maximum distance from said radial bore of said piston when the latter is at the end of its suction stroke; supply conduit means communicating with the interior of said cylinder means for supplying fuel thereto; engine-driven pump means communicating with said tank and supply conduit means for pumping fuel along said supply conduit means to said cylinder means at pressures which increase and decrease with an increase and a decrease in the engine speed, respectively; pressure-responsive means communicating With said supply conduit means and cooperating with said cylinder means for urging the latter in opposition to said first spring means in a direction locating said radial bore of said cylinder means closer to said radial bore of said piston when the later is at the end of its suction stroke, said rst spring means forming the only means opposing movement of said cylinder means in said direction from said rest position thereof during a first increment of movement of said cylinder means; and second spring means cooperating with said cylinder means for opposing movement thereof in said direction only during a second increment of movement of said cylinder means subsequent to said first increment, said first increment of movement of said cylinder means providing a reduction in the amount of fuel delivered by said injection pump to the engine in the speed range from starting to idling speed, and said second increment of movement of said cylinder means providing a reduction in the amount of fuel delivered to the engine in the speed range from idling speed to maximum speed at full load.

l0. In an injection pump, in combination, cylinder means having a Wall portion formed with a radial bore; support means supporting said cylinder means for axial movement; an axially bored piston coaxial with and slidable Within said cylinder means; means for reciprocating said piston along pressure and suction strokes, said piston having a free end located at all times in said cylinder means and said axial bore of said piston communicating at all times with the interior of said cylinder means, said piston being formed adjacent said free end thereof with a radial bore which communicates with said radial bore of said cylinder means during part of the stroke of said piston; a fuel tank; return-flow conduit means communieating with said radial bore of said cylinder means and said tank for conveying fuel from said radial bore of said cylinder means back to said tank; first spring means cooperating `with said cylinder means for yieldably maintaining the latter in a rest position Where said radial bore thereof is at its maximum distance from said radial bore of said piston when the latter is at the end of its suction stroke; supply conduit means communicating with the interior of said cylinder means for supplying fuel thereto; engine-driven pump means communicating with said tank and supply conduit means for pumping fuel along said supply conduit means to said cylinder means at pressures which increase and decrease with an increase and a decrease in the engine speed, respectively; pressure-responsive means communicating with said supply conduit means and cooperating with said cylinder means for urging the latter in opposition to said first spring means in a direction locating said radial bore of said cylinder means closer to said radial bore of said piston when the latter is at the end of its suction stroke, said first spring means forming the only means opposing movement of said cylinder means in said direction from said rest position thereof during a first increment of movement of said cylinder means; second spring means cooperating with said cylinder means for opposing movement thereof in said direction only during a second increment of movement of said cylinder means subsequent to said rst increment; and third spring means cooperating with said cylinder means for opposing movement thereof in said direction only subsequent to said second increment of movement of said cylinder means, said first increment of movement of said cylinder means providing a reduction in the fuel output of the injection pump in the speed range from starting to idling speed, said second increment providing a reduction in the fuel output of the injection pump from idling speed to the maximum engine speed at full load, and movement of said cylinder means beyond said Second increment reducing the fuel output of the fuel pump in the speed range from maximum speed at rfull load to the highest permissible engine speed.

ll. In an injection pump, in combination, cylinder means having a Wall portion formed with a radial bore; support means supporting said cylinder means for axial movement; an axially bored piston coaxial With land slidable within said cylinder means; means for reciprocating said piston along pressure and suction strokes, said pis-ton having a free end located at all times in said `cylinder means and said axial 'bore of said piston communicating at all times with the interior of said cylinder means, said piston being formed adjacent said free end thereof with a radial bore which communicates with said radial bore of said cyinder means during part of the stroke of said piston; a fuel tank; return-flow conduit means communicating With said radial bore of said cylinder means -and said tank for conveying fuel from said radial bore of -said cylinder means back to said tank; first spring means cooperating With said cylinder means for yieldably maintaining the latter in a rest position Where said radial bore thereof is at its maximum distance from Said radial bore of said piston when the latter is at the end of its suction stroke; supply conduit means communicating with the interior of said cylinder means for supplying fuel thereto; engine-driven pump means communicating with said tank and supply conduit means for pumping fuel along said supply conduit means to said cylinder means at pressures which increase and decrease with an increase and a decrease in the engine speed, respectively; pressure-responsive means communicating with said supply conduit means and cooperating with said cylinder means for urging the latter in opposition to said first Spring means in a direction locating said radial bore of said cylinder means closer to said radial bore of said piston when the latter is at the end of its suction stroke, said first spring means forming the only means opposing movement of said cylinder means in said direction from said rest position thereof during a first increment of movement of said cylinder means; and second spring means cooperating with said cylinder means for opposing movement thereof in said direction only during a second increment of movement of said cylinder means subsequent to said first increment, said second spring means being operative only during said second increment of movement of said cylinder means.

12. In an injection pump, in combination, cylinder means having a wall portion formed with a radial bore; support means supporting said cylinder means for axial movement; an axially bored piston coaxial with and slideable within said cylinder means; means for reciprocating said piston along pressure and suction strokes, said piston having a free end located at all times in said cylinder means and said axial bore of said piston communicating at all times with the interior of said cylinder means, said piston being formed adjacent said free end thereof with a radial bore which communicates with said radial bore of said cylinder means during part of the stroke of said piston; a fuel tank; return-flow conduit means communicating with said radial bore of said cylinder means and said tank for conveying fuel from said radial bore of said cylinder means back to said tank; first spring means cooperating With said cylinder means for yieldably maintaining the latter in a rest position Where said radial bore thereof is at its maximum distance from said radial bore of said piston when the latter is .at the end of its suction stroke; supply conduit means communicating with the interior of said cylinder means for supplying fuel thereto; engine-driven pump means communicating with said tank and supply conduit .means for pumping fuel along said supply conduit means to said cylinder means at pressures which increase and decrease with an increase and a decrease in the engine speed, respectively; pressure-responsive means communicating with said supply conduit means and cooperating with said cylinder means for urging the latter in opposition to said first spring means in a direction locating said radial bore of said cylinder means closer to said radial bore of said piston when the latter is at the end of its suction stroke, said first spring means forming the only means opposing movement of said cylinder means in said direction from said rest position thereof during a first increment of movement of said cylinder means; second spring means cooperating with said cylinder means for opposing movement thereof in said direction only during a second increment of movement of said cylinder means subsequent to said first increment; and third spring means cooperating with said .cylinder means for opposing movement thereof in said direction only subsequent to said second increment of movement of said cylinder means, said first spring means opposing movement of said cylinder means in said direction at all times and said second spring means opposing movement of said cylinder means in said direction only during said second increment of movement thereof.

13. 1n an injection pump, in combination, cylinder means having a Wall portion formed With a radial bore; support means supporting said cylinder means for axial movement; an axially bored piston coaxial with and slidable within said cylinder means; means for reciprocating said piston along pressure and suction strokes, said piston having a free end located at all times in said cylinder means and said axial bore of said piston communicating at all times with the interior of said cylinder means, said piston being formed adjacent said free end thereof with a radial bore which communicates with said radial bore of said cylinder means during part of the stroke of said piston; a fuel tank; return-flow conduit means communicating with said radial bore of said cylinder means and said tank for conveying fuel from said radial bore of said cylinder means back to said tank; first spring means cooperating With said cylinder means for yieldably maintaining the latter in a rest position Where said radial bore thereof is at its maximum distance from said radial bore of said piston when the latter is at the end of its suction stroke; supply conduit means communicating With the interior of said cylinder means for supplying fuel thereto; engine-driven pump means communicating with said tank and supply conduit means for pumping fuel along said supply conduit means to said cylinder means at pressures which increase and decrease With an increase and a decrease in the engine speed, respectively; pressure-responsive means communicating With said supply conduit means and cooperating with said cylinder means -for urging the latter in opposition to said first spring means in a direction locating said radial bore of said cylinder means closer to said radial bore of said piston when the latter is at the end of its suction stroke, said first spring means forming the only means opposing movement of said cylinder means in said direction from said rest position thereof during a first increment of movement of said cylinder means; second spring means cooperating with said cylinder means for opposing movement thereof in said direction only during a second increment of movement of said cylinder means subsequent to said first increment; and third spring means cooperating With said cylinder means for opposing movement thereof in said direction only subsequent to said second increment of movement of said cylinder means, said third spring means having no inuence on the movement of said cylinder means during said first and second increments of movement thereof.

i 15 t v Y 14. In an injection pump, in combination, cylinder means having a Wall portion formed with a radial bore; support means supporting said cylinder means for axial movement; an axially bored piston coaxial with and slidable Within said cylinder means; means for reciprocating 5 said piston along pressure and suction strokes, said piston having a free end located at all times in said cylinder means and said axial bore of said piston communicating at all times with the interior of said cylinder means, said piston being formed adjacent said free end thereof with a radial bore which communicates with said radial bore of said cylinder means during part of the stroke of said piston; a fuel tank; return-110W conduit means communieating with said radial bore of said cylinder means and said tank for conveying fuel from said radial bore of said cylinder means back to said tank; rst spring means cooperating with said cylinder means for yieidably maintaining the latter in a rest position where said radial bore thereof is at its maximum distance from said radial bore of said piston when the latter is at the end of its suction stroke; supply conduit means communicating with the interior of said cylinder means for supplying fuel thereto; engine-driven pump means communicating with said tank and supply conduit means for pumping fuel along said supply conduit means to said cylinder means at pressures which increase and decrease With an increase and a decrease in the engine speed, respectively; pressure-responsive means communicating with said supply conduit means and cooperating with said cylinder means for urging the latter in opposition to said first spring means in a diree- 3D tion locating said radial bore of said cylinder means closer to said radial bore of said piston when the latter is at the end of its suction stroke, said iirst spring means forming the only means opposing movement of said cylinder means in said direction from said rest position thereof during a rst increment of movement of said cylinder means; second spring means cooperating with said cylinder means for opposing movement thereof in said direction only during a second increment of movement of said cylinder means subsequent to said rst increment; and third spring means cooperating With said cylinder means for opposing movement thereof in said direction only subsequent to said second increment of movement of said cylinder means, said rst spring means acting at all times to oppose movement of said cylinder means from said rest position thereof in said direction and urging said cylinder means back toward said rest position with an increasing force as said cylinder means moves increasingly away from said rest position thereof, said second spring means acting only during said second increment of movement to oppose movement of said cylinder means in said direction, and said third spring means being operative to oppose movement of said cylinder means in said direction only subsequent to said second increment of movement thereof.

References Cited in the tile of this patent UNITED STATES PATENTS 1,292,981 Weiss Jan. 28, 1919 2,810,376 Aldinger Oct. 22, 1957 FOREIGN PATENTS 697,542 Great Britain Sept. 23, 1953 

